Fluid distribution system



1965 T. J. HUDDLESTON FLUID DISTRIBUTION SYSTEM 3 Sheets-Sheet 1 Filed June 7, 1963 m L D L UD 0 DLR Hm MET R F QVN F. O IE0 R LLC WU H W llll Rm n 2 WE 4 so PRESSURE RECORDER CONTROLLER I I 52 I 5! W my mm v0 W D U H I FIG. 3

ATTORNEYS Oct. 19, 1965 T. J. HUDDLESTON 3,212,278

FLUID DISTRIBUTION SYSTEM Filed June '7, 1963 3 Sheets-Sheet 2 I. O n 10 N A A m 1 Pl I m I 1 I I f r it o I w m N m I m 1 I w w m n h "E i l-| h bl F 1 C I 2 I fi r v I I INVENTOR. T. J. HUDDLESTON BY IQ! 1965 T. J. HUDDLESTON 3,212,278

FLUID DISTRIBUTION SYSTEM Filed June '7, 1963 3 Sheets-Sheet 5 INVENTOR. T. J. HUDDL ESTON A T TORNEVS United States Patent 3,212,278 FLUID DISTRIBUTION SYSTEM Thomas .I. Huddleston, Bartlesville, 011121., assignor to Phillips Petroleum Company, a corporation of Delaware Filed June 7, 1963, Ser. No. 286,313 4 Claims. (Cl. 6223) This invention relates to method and apparatus for providing a substantially uniform distribution of a fluid which has two phases. In one aspect the invention relates to method and apparatus for feeding a uniform concentration of both liquid and vapor into a plurality of flow paths. In another aspect the invention relates to method and apparatus for feeding a substantially uniform concentration of liquid and vapor into a multiple passage heat exchanger. In a still further aspect the invention relates to method and apparatus for flashing a liquid, recovering the flashed liquid and the flashed vapors, and passing a substantially uniform concentration of the flashed liquid and flashed vapors into a plurality of flow paths.

In the liquefication of natural gas by low temperature refrigeration for the production of liquefied natural gas or for recovery of gaseous helium therefrom, it is desirable in some instances to reduce the pressure on the liquefied gases before the separated liquids are passed through a heat exchanger in order to have the liquefied gases at a pressure at which substantially all of the liquefied gases will be vaporized by passage through the heat exchanger. When the pressure is reduced, flashing occurs, and it is difficult to pass a uniform concentration of the resulting two phase fluid into the various passages of the heat exchanger. If most of the flashed liquid is allowed to pass through some of the passes and the flashed vapor is allowed to pass through the other passes, the amount of liquid vaporized will be decreased, resulting in less heat being transferred as well as an unequal distribution of the heat. For a maximum transfer of heat, it is desirable for a uniform concentration of the various constituents of the fluid to pass into each of the passes in the heat exchanger.

In accordance with the invention it has been discovered that these difliculties can be overcome by separating the two phase fluid into a liquid portion and a vapor portion, introducing a substantially equal portion of the liquid portion into each of the plurality of flow paths through the heat exchanger, and introducing substantially equal portions of the vapor portion into each of the plurality of flow paths.

In one particular embodiment of the invention there is provided a heat exchanger having a tube sheet, closure means mounted over said tube sheet to form a chamber, a plurality of tubes, one end of each of said plurality of tubes extending substantially vertically through said tube sheet and into said chamber a predetermined distance, a plurality of perforations in each of said tubes spaced vertically along said predetermined distance, means for introducing the two phase fluid into said chamber to form a reservoir of liquid in said chamber around said tubes and a reservoir of vapor in said chamber above said reservoir of liquid, said predettermined distance being greater than the depth of said reservoir of liquid. In one particular process in which the invention is particularly applicable the gas to be cooled is passed in indirect heat exchange with the fluid in that portion of the plurality of tubes below said tube sheet to condense at least a portion of said gas. The thus cooled and at least partially condensed gas is passed into a phase separator. The condensed liquid is withdrawn from the phase separator and at least a portion of the withdrawn liquid is passed through a throttling valve to reduce the pressure of the liquid and effect a further cooling of the liquid. The throttling action results in a partial vaporization of the liquid to form a two phase fluid. The two phase fluid is passed to the means for introducing the two phase fluid into the chamber of the heat exchanger. The two phase fluid separates in the chamber to form the reservoir of liquid and the reservoir of vapor. Liquid from the reservoir of liquid enters each of the plurality of tubes by Way of the perforations which are below the level of the liquid in the chamber. Similarly vapor from the reservoir of vapor passes into each of the plurality of tubes by way of the perforations located above the level of the liquid. The perforations are sized to provide an equal flow of liquid into each of the plurality of tubes and an equal flow of vapor into each of the plurality of tubes. The streams of liquid and vapor thus produced pass through the tubes into indirect heat exchanging relationship with additional gas to be cooled. The vapor can be withdrawn from phase separator and passed to further processing. The products of the further processing (or the vapors from the phase separator) can be passed in indirect heat exchanging relationship with additional gas to be cooled in parallel with the heat exchanging provided by the fluid passing through said plurality of tubes.

Accordingly it is an object of the invention to provide method and means for obtaining a substantially uniform distribution of a two phase fluid into a plurality of flow paths. Another object of the invention is to provide a uniform distribution of heat in a heat exchanger. Another object of the invention is to provide for maximum transfer of heat in a heat exchanger. A still further object of the invention is to provide substantially uniform concentration of both liquid and vapor into a plurality of flow paths in a heat exchanger. Another object of the invention is to provide improved method and means for partially liquefying a gas stream by auto refrigeration.

Other objects, aspects and advantages of the invention will be apparent from a study of the disclosure, the drawings and the appended claims to the invention.

In the drawings FIGURE 1 is a diagrammatic representation of a low temperature refrigeration separation process embodying the invention; FIGURE 2 is an elevation view of one embodiment of apparatus for carrying out the invention; FIGURE 3 is a cross sectional view of the apparatus of FIGURE 2 taken along the line 33; FIGURE 4 is an elevation view of a second embodiment of apparatus for carrying out the invention; and FIGURE 5 is a cross sectional view of the apparatus of FIGURE 4 taken along the line 55.

While the invention is applicable to various processes for liquefying a portion of a gas feed stream, for purposes of illustration the invention will be described in terms of a process for the recovery of helium from a natural gas stream. It is equally applicable to a process for substantially complete liquefaction of natural gas and also for liquefaction of air, hydrogen, ammonia, chlorine, etc.

Referring now to the drawing in detail and to FIGURE 1 in particular natural gas containing hydrocarbons, nitrogen, and helium is passed through line 11 into and through parallel flow paths 12, 13 and 14 of indirect heat exchanger 15, wherein the gas is substantially cooled to the extent that a portion thereof is liquefied. The gas can be partially or totally liquefied and passed through a throttle valve before entering separator 17, if desired. The thus cooled and partially condensed gas is passed by way of line 16 into a liquid gas separator 17. A valve 18 can be positioned in line 11 and manipulated by a pressure recorder controller 19 responsive to the pressure of the gas in line 11 downstream of valve 18 to maintain such pressure substantially constant.

The vapors from liquid gas separator 17 are withdrawn through line 21 and passed to a separation zone 22 Patented Oct. 19, 19 5 wherein a further separation can be made, if desired. Separation zone 22 can be any suitable means, such as, for example, a series of heat exchangers and liquid gas separators. The details of suitable means for separation zone 22 in a helium recovery system are set forth in copending application Serial No. 218,985, filed August 23, 1962, by L. G. Kitchen. Exemplary of such further processing, a crude helium stream, a low B.t.u. gas, and a residue gas can be obtained in separation zone 22. The crude helium stream is passed through line 23 into and through flow path 24 of indirect heat exchanger wherein the crude helium stream is passed in indirect heat exchanging relationship with additional natural gas passing through flow paths 12, 13 and 14. The warmed crude helium stream passes from flow path 24 into line 25 and can be withdrawn from the system. A valve 26 can be positioned in line 25 and manipulated by pressure recorder controller 27 to maintain the pressure in line 25 upstream of valve 26 substantially constant, is desired. A low B.t.u. gas obtained in separation zone 22 is passed through line 28 into and through flow path 29 in indirect heat exchanger 15 wherein the low B.t.u. gas is passed in indirect heat exchanging relationship with additional natural gas passing through flow paths 12, 13 and 14. The warmed low B.t.u. gas passes from flow path 29 and can be withdrawn from the system by way of line 31. A valve 32 can be positioned in line 31 and manipulated by pressure recorder controller 33 to maintain the pressure of the fluid in line 31 upstream of valve 32 substantially constant, if desired. The residue gas obtained in separation zone 22 is passed through line 34 into and through flow path 35 of indirect heat exchanger 15 wherein the residue gas is passed in indirect heat exchanging relationship with additional natural gas passing through flow paths 12, 13 and 14. The warmed residue gas passes from flow path 35 and can be withdrawn from the system by way of line 36. A valve 37 can be positioned in line 36 and manipulated by a pressure recorder controller 38 to maintain the pressure of the fluid in line 36 upstream of valve 37 substantially constant, as desired.

The liquid in liquid gas separator 17 is withdrawn therefrom by way of line 41. A throttle valve 42 is positioned in line 41 to effect a reduction in the pressure of the liquid passing through line 41 and thus a further cooling of such liquid. If desired throttle valve 42 can be manipulated by a liquid level controller 43 to maintain the liquid level in liquid gas separator 17 substantially constant. When the liquid passes through throttle valve 42, flashing occurs resulting in a two phase fluid downstream of valve 42. This two phase fluid passes into two phase fluid distribution means which is utilized to effect an even distribution of each of the two fluid phases in parallel flow paths 43-48 of indirect heat exchanger 15 wherein the two phase fluid is passed in indirect heat exchange relationship with additional natural gas passing through flow paths 12, 13 and 14. The introduction of the two phase fluid into flow paths 43-48 is in such a manner that the amount of liquid passing into each of flow paths 43-48 is substantially the same and similarly the amount of vapor passing into each of flow paths 43-48 is substantially the same. The efliuent from flow paths 43-48 is collected and withdrawn from the system by way of line 49. A valve 51 can be positioned in line 49 and manipulated by pressure recorder controller 52 to maintain the pressure in line 49 upstream of valve 51 substantially constant, if desired. The flow conditions through flow paths 43 through 48 are such that substantially all of the liquid passing through flow paths 43-48 is vaporized by the transfer of heat thereto from the natural gas feed stream passing through flow paths 12, 13 and 14. By this transfer of heat, the feed gas is partially or totally liquefied depending on conditions of temperature and pressure imposed on the system.

Referring now to FIGURE 2 phase distribution device 40 comprises a horizontally positioned tube sheet 61, a suitable closure means such as hood 62, positioned over the tube sheet to form chamber 63, and a plurality of tubes 64, 65, 66, 67, 68 and 69. Tubes 64-69 are spaced apart from each other and from conduit 41 in a suitable array, such as the radial array shown in FIG- URE 3. Tubes 64-69 extend substantially vertically through tube sheet 61 and into chamber 63 a predetermined distance. As shown with respect to tube '69 in FIGURE 2, each of tubes 64-69 contains a plurality of perforations 71 spaced vertically along the length of the portion of the tube which is extended into chamber 63. The two phase fluid resulting from the throttling action of valve 42 is passed through from conduit 41 into chamber 63 wherein the two phase fluid separates to form a reservoir of liquid and a reservoir of vapor. Liquid passes into each of tubes 64-69 by way of the perforations 71 which are below the level of the liquid. Vapors enters each of tubes 64-69 by way of perforations 71 which are above the level of the liquid. The upper ends of tubes 64-69 are preferably capped to prevent liquid from splashing into the various tubes in an uneven manner. The utilization of a plurality of perforations spaced along the vertical length of each tube is particularly advantageous in that it automatically pro vides a regulation of the ratio of liquid to vapor passing into each tube responsive to the variations in the ratio of liquid to vapor in the two phase fluid entering by Way of conduit 41. Thus if the percentage of liquid in conduit 41 increases, the level of the liquid reservoir in chamber 63 rises. The increase in the liquid level causes liquid to flow through an increased number of perforations and thus increases the rate of flow of liquid into each one of tubes 64-69. At the same time the increase in liquid level reduces the number of perforations available to pass vapor from chamber 63 into tubes 64-69, thus corresponding to the reduction in the percentage of vapor in the two phase fluid in conduit 41. This regulation of the rate of passing liquid from chamber 63 into tubes 64-69 due to variation in total cross section area of liquid flow through the perforations as well as the changes in the pressure head is faster and more sensitive than that which could be accomplished by a single perforation in the lower part of each tube which would pass liquid at a rate depending only upon the pressure head due to the height of the liquid level. Thus it is readily seen that two phase distribution device 40 effects the introduction of substantially equal amounts of liquid into each of tubes 64-69 and the introduction of substantially equal amounts of vapors into each of tubes 64-69.

Tubes 64-69 pass the two phase fluid introduced therein into the heat exchanger flow paths provided by conduits 43-48, respectively. Conduits 43 and 44 and crude helium stream flow path conduit 24 pass through one end of header 72 and into and through conduit 14 into header 73. Conduit 14 is sufliciently large in cross sectional area to permit conduits 24, 43 and 44 to pass through the interior thereof in a length wise manner. Two phase fluid conduits 45 and 46 and low B.t.u. gas flow path conduit 29 pass through one end of header 74 and into the inlet and through the interior of conduit 13 to header 75. Similarly two phase flow path conduits 47 and 48 and residue gas flow path conduit 35 pass through one end of header 76 and into and through the interior of conduit 12 into header 77.

Conduits 43 and 44 pass through header 73 and are connected with conduit 49. Similarly conduits 45 and 46 and conduits 47 and 48 pass through headers 75 and 77, respectively, and are connected to conduit 49. Conduit 24 passes from header 73 and is connected to conduit 25 while conduits 29 and 35 pass through headers 75 and 77 and are connected to conduits 31 and 36, respectively. Feed gas from conduit 11 is passed into the interior of headers 73, 75 and 77 and then through conduits 14,

13 and 12 into headers 72, 74 and 76, respectively. The cooled and partially liquefied feed gas is withdrawn from headers 72, 74 and 76 and is passed into conduit 16 and then into separator 17, is in FIGURE 1. Conduits 12, 13 and 14 containing their respective internal conduits are positioned in the form of helixes to provide maximum length of heat exchanger flow paths in a convenient configuration. Heat exchanger 15 can be filled with suitable insulating material as is well known in the art.

Referring now to FIGURE 4 there is illustrated apparatus which can be used as an alternative embodiment of the apparatus of FIGURE 2. Heat exchanger 15 comprises a cylindrical shell 81 which is closed at one end by means of hood 62 and at the other end by hood 82. A second tube sheet 83 is positioned within shell 81 and spaced from tube sheet 61 by means of spacer members 84 and 85 to form three chambers 86, 87 and 88 as illustrated in FIGURE 5. Tube sheet 89 is positioned within shell 81 adjacent hood 82 to form a chamber 90 between tube sheet 89- and hood 82. Tube sheet 91 is positioned in shell 81 and spaced above tube sheet 89 by means of spacer members 92 and 93 to form three chambers 94, 95 and 96 corresponding to chambers 86, 87 and 88, respectively. Tubes 64-69 are in fluid communication between chambers 63 and 90 with the fluid being withdrawn from chamber 90 by way of conduit 49. A tube 35 is positioned between tube spacers 83 and 91 and in fluid communication between chambers 86 and 94, and tube 29 is positioned between tube sheets 83 and 91 and in fluid communication between chambers 87 and 95'. Similarly a tube 24 is positioned between tube sheets 83 and 91 and in fluid communication between chambers 88 and 96. Conduits 34, 28 and 23 are connected in fluid communication with chambers 86, 87 and 88, respectively, while conduits 36, 31 and 25 are connected to chambers 94, 95 and 96, respectively. Conduit 11 communicates with the interior of shell 81 at the lower end thereof while conduit 16 communicates with the interior of shell 81 at the upper end thereof, thus providing a flow path for the feed gas between the various tubes inside of shell 81.

While the heat exchanger 15 has been illustrated with flow paths 12, 13 and 14; 24, 29 and 35; and 43-48, it is obvious that any desired number of flow paths can be utilized for each of the streams passing through heat exchanger 15. Also while the invention has been illustrated in connection with a refrigeration system for the recovery of helium, the invention can be utilized any time that is desired to provide a substantially uniform distribution of each phase of a two phase fluid through a plurality of flow paths.

The following example is presented in further illustration of the invention and is not to be unduly construed in limitation thereof.

Example The invention as shown in FIGURE 1 was operated with natural gas and the following performance data taken:

Vapor Feed Product, Liquid Compositions Stream l1 Combined Product,

Streams Stream 49 25,31 and 36 4 0 OcnLOrOv-nh Measured Flow Rates, Standard cu. ft./min Pressures, p.s.i.a

Run N0 1 2 3 4 5 6 7 8 Temperature, F.:

Separator, l7... l32 131 132 132 143 l39 138 l38 lashed Liquid. 40-.. 186 186 181 177 185 181 -180 181 Flashed Liquid- Outlet of 43 85 93 88 83 83 78 77 Outlet of 44 84 93 87 82 82 80 77 76 Outlet of 45 88 95 92 88 88 87 82 Outlet of 46 88 95 92 88 88 86 84 81 Outlet of 47 88 96 92 89 88 87 85 83 Outlet of 48 87 95 92 88 88 88 85 83 Feed Stream 11 92 100 97 94 95 94 92 89 Combined Vapor Product, 25, 31, 36 86 93 90 86 85 82 80 77 Liquid Prodnot, 49 87 91 88 87 85 83 81 The essentially constant temperatures of the flashed liquid at the outlets of the exchanger tubes (Nos. 43 thru 48) prove that liquid and vapor were equally distributed among these tubes by distributor 40. If distribution had been non-uniform, that is if most of the liquid had gone into one tube, then the outlet of this tube would have been very cold in comparison with the remainder of the tubes. Simultaneously, the outlet of a tube transporting only vapor would have been very considerably warmer than the remainder of the tubes. Measurements of the outlet tube temperatures were thus made to determine the performance of the invention.

Reasonable variation and modification are possible within the scope of the foregoing disclosure, the drawing and the appended claims.

I claim:

1. Apparatus for utilizing a multiple constituent high pressure liquid stream as a cooling fluid in an indirect heat exchanger having a plurality of flow paths therethrongh and wherein it is desirable that substantially all of the cooling fluid be vaporized in passing through said heat exchanger although said liquid stream is at a pressure higher than the pressure at which substantially all of said liquid stream would be vaporized by being passed through said heat exchanger, and wherein said liquid stream would have a liquid phase and a gas phase upon the pressure of said liquid stream being reduced to said pressure at which substantially all of said liquid would be vaporized by being passed through said heat exchanger, comprising an indirect heat exchanger having a plurality of flow paths .therethrough, means for passing a multiple constituent gas feed stream under elevated pressure through said heat exchanger in indirect heat exchanging relationship with the fluid contents of said plurality of flow paths to partially liquefy said gas feed stream, a phase separator, means for passing the thus cooled and partially liquefied gas into said phase separator, means for withdrawing a multiple constituent high pressure liquid stream from said phase separator, means for reducing the pressure on said liquid stream to a pressure at which substantially all of said liquid stream would be vaporized by being passed through said plurality of flow paths of said heat exchanger, thus producing a two phase fluid, a tube sheet, closure means mounted over said tube sheet to form a chamber, a plurality of tubes, one end of each of said plurality of tubes extending substantially vertically through said tube sheet and into said chamber, said one end of each of said plurality of tubes being closed, a plurality of perforations in each of said tubes spaced vertically along the portion of said tube in said chamber for a predetermined distance, means for introducing said two phase fluid into said chamber to form a reservoir of liquid in said chamber around said tubes of a height less than the height of the highest one of said plurality of perforations and a reservoir of vapor in said chamber above said reservoir of liquid, said predetermined distance being greater than the depth of said reservoir of liquid, the other end of each of said plurality of tubes being in fluid communication with the inlet of a respective one of said plurality of flow pathsin said heat exchanger to provide for the passage of substantially equal portions of the vapor from said reservoir of vapor into each of said plurality of flow paths and to provide for the introduction of substantially equal portions of the liquid from said reservoir of liquid into the gas flowing through each of said tubes to thus provide for the passage of a uniform concentration of the various constituents of said high pressure liquid through each of said flow paths, means for withdrawing the warmed fluid from the outlet end of each of said plurality of flow paths in said heat exchanger, means for withdrawing a vapor stream from said phase separator, and means for passing said vapor stream through said heat exchanger in indirect heat exchanging relationship with said gas feed stream.

2. A method of separating a multiple constituent gas feed int-o at least two fractions which comprises passing said gas feed under elevated pressure through an indirect heat exchanging zone in indirect heat exchanging relationship with the fluid contents of a plurality of flow paths contained in said indirect heat exchanging zone to cool said gas feed sufficiently to liquefy a portion thereof, passing the thus cooled and partially liquefied gas feed into a liquid-gas separation zone, withdrawing a multiple constituent liquid from said separation zone, the pressure of the thus withdrawn liquid being higher than the pressure at which substantially all of said withdrawn liquid would be vaporized by being passed through said plurality of flow paths in said heat exchanging zone, and wherein said withdrawn liquid would have a liquid phase and a gas phase upon the pressure of said withdrawn liquid being reduced to said pressure at which substantially all of said withdrawn liquid would be vaporized by being passed through said plurality of flow paths in said heat exchanging zone, reducing the pressure of said withdrawn liquid to a pressure at which substantially all of said withdrawn liquid would be vaporized by being passed through said plurality of flow paths, thus producing a two phase fluid,

separating said'two phase fluid into a liquid component and a gas component, dividing said gas component into substantially equal parts equal in number to the number of said flow paths and introducing each of the substantially equal parts of the gas component into a respective one of said plurality of flow paths, dividing said liquid component into a plurality of substantially equal parts equal in number to the number of .said flow paths and introducing each of the substantially equal parts of said liquid component into the gas flowing through a respec-v tive one of said plurality of flow paths to provide for the passage through each of said plurality of flow paths a uniform concentration of the various constituents of said withdrawn liquid. withdrawing vapor from said separation zone, passing the thus withdrawn vapor through said indirect heat exchanging zone in indirect heat exchanging relationship with an additional portion of said gas feed, and recovering the warmed fluid from the outlet ends of each of said plurality of flow paths as a product of the process.

3. A method in accordance with claim 2 wherein said gas feed is natural gas.

4.A method in accordance with claim 2 wherein said gas feed is air.

References Cited by the Examiner UNITED STATES PATENTS 1,020,102 3/12 Von Linde 6223 1,804,432 5/31 Pollitzer 6223 XR 1,876,551 9/32 Barstow -Q 6223 2,168,404 8/39 Grant 62--525 2,220,595 1/40 Anderson 62525 2,237,239 4/41 Smith 62525 XR 2,521,369 9/50 Holm 6213 XR 2,555,055 5/51 Ort 62525 2,591,658 4/52 Haringhuizen 6223 2,682,157 6/54 Boling 6213 2,716,333 8/55 Collins 6213 2,940,271 6/ Jackson.

2,973,834 3/61 Cicaleze.

NORMAN YUDKOFF, Primary Examiner. 

1. METHOD OF SEPARATING A MULTIPLE CONSTITUENT GAS FEED INTO AT LEAST TWO FRACTIONS WHICH COMPRISES PASSING SAID GAS FEED UNDER ELEVATED PRESSURE THROUGH AN INDIRECT HEAT EXCHANGING ZONE IN INDIRECT HEAT EXCHANGING RELATIONSHIP WITH THE FLUID CONTENTS OF A PLURALITY OF FLOW PATHS CONTAINED IN SAID INDIRECT HEAT EXCHANGING ZONE TO COOL SAID GAS FEED SUFFICIENTLY TO LIQUEFY A PORTION THEREOF, PASSING THE THUS COOLED AND PARTIALLY LIQUEFIED GAS FEED INTO A LIQUID-GAS SEPARATION ZONE, WITHDRAWING A MULTIPLE CONSTITUENT LIQUID FROM SAID SEPARATION ZONE, THE PRESSURE OF THE THUS WITHDRAWN LIQUID BEING HIGHER THAN THE PRESSURE AT WHICH SUBSTANTIALLY ALL OF SAID WITHDRAWN LIQUID WOULD BE VAPORIZED BY BEING PASSED THROUGH SAID PLURALITY OF FLOW PATHS IN SAID HEAT EXCAHNGING ZONE, AND WHEREIN SAID WITHDRAWN LIQUID WOULD HAVE A LIQUID PHASE AND A GAS PHASE UPON THE PRESSURE OF SID WITHDRAWN LIQUID BEING REDUCED TO SAID PRESSURE AT WHICH SUBSTANTIALLY ALL OF SAID WITHDRAWN LIQUID WOULD BE VAPORIZED BY BEING PASSED THROUGH SAID PLURALITY OF FLOW PATHS IN SAID HEAT EXCHANGING ZONE, REDUCING THE PRESSURE OF SAID WITHDRAWN LIQUID TO A PRESSURE AT THICH SUBSTANTIALLY ALL OF SAID WITHDRAWN LIQUID WOULD BE VAPORIZED BY BEING PASSED THROUGH SID PLURALITY OF FLOW PATHS, THUS PRODUCING A TWO PHASE FLUID, SEPARATING SAID TWO PHASE FLUID INTO A LIQIUD COMPONENT 